[Scummvm-cvs-logs] SF.net SVN: scummvm:[47595] scummvm/trunk/engines/sci/engine/vm.cpp

[thebluegr at users.sourceforge.net]

Revision: 47595
          http://scummvm.svn.sourceforge.net/scummvm/?rev=47595&view=rev
Author:   thebluegr
Date:     2010-01-27 12:13:39 +0000 (Wed, 27 Jan 2010)

Log Message:
-----------
Added support of the subtraction of two pointers, when they got the same segment. This operation will yield a number, like in C, and it's used by script 385 in Castle of Dr. Brain (the hangman script). Fixes exiting room 360 (the puzzle room) in Castle of Dr. Brain

Modified Paths:
--------------
    scummvm/trunk/engines/sci/engine/vm.cpp

Modified: scummvm/trunk/engines/sci/engine/vm.cpp
===================================================================
--- scummvm/trunk/engines/sci/engine/vm.cpp	2010-01-27 11:18:05 UTC (rev 47594)
+++ scummvm/trunk/engines/sci/engine/vm.cpp	2010-01-27 12:13:39 UTC (rev 47595)
@@ -763,7 +763,7 @@
 
 		case 0x02: // sub
 			r_temp = POP32();
-			if (r_temp.segment || s->r_acc.segment) {
+			if (r_temp.segment != s->r_acc.segment) {
 				reg_t r_ptr = NULL_REG;
 				int offset;
 				// Pointer arithmetics!
@@ -783,8 +783,11 @@
 
 				s->r_acc = pointer_add(s, r_ptr, -offset);
 
-			} else
+			} else {
+				// We can subtract numbers, or pointers with the same segment,
+				// an operation which will yield a number like in C
 				s->r_acc = make_reg(0, r_temp.offset - s->r_acc.offset);
+			}
 			break;
 
 		case 0x03: // mul


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